Enhanced Thermoelectric Properties of Exfoliated BN Nanosheets/Single-Walled Carbon Nanotube Composite Films for Applications in Flexible Electronics

Single-walled carbon nanotube (SWCNT)-based flexible thermoelectric films exhibit potential application in wearable electronics due to their good electrical conductivity (σ) and high flexibility. Nevertheless, the low Seebeck coefficient ( S ) greatly limits their thermoelectric application. The high S of inorganic boron nitride nanosheets is expected to make up for the low S of SWCNT. In this work, exfoliated boron nitride nanosheets (EBNS) are first prepared by solvothermal exfoliation of hexagonal boron nitride (h-BN), which are composited with SWCNT through a simple mixing and filtration method to prepare self-supporting EBNS/SWCNT films with improved thermoelectric properties. Here, the energy filtering effect at the EBNS/SWCNT interface significantly improves the S values of the films. The results show that the maximum S of the EBNS/SWCNT at room temperature is 50.6 μV K –1 and the maximum power factor (PF) is 116.1 μW m –1 K –2 at the EBNS/SWCNT mass ratio of 7.5%. Finally, six pairs of p-type EBNS/SWCNT films and n-type copper sheets are connected in series to assemble a self-powered thermoelectric device, which demonstrates an open-circuit voltage of 8.1 mV and an output power of 550 nW under a temperature difference of 60 K. Therefore, this work provides a simple and effective method to improve the performance of carbon nanotube-based thermoelectric materials.